The present specification relates generally to the automotive arts. More specifically, the present specification relates to a control system and/or method that adjusts or otherwise regulates the output voltage of a vehicle's electric power generator in response to a detected state of charge (SOC) of the vehicle's battery. Particular application is found in connection with an electrical system of a motor vehicle (e.g., an automobile or other vehicle driven by an internal combustion engine), and the specification makes particular reference thereto. However, it is to be appreciated that aspects of the present subject matter are also amenable to other like applications.
As is known in the art, many automotive vehicles generally include an internal combustion or other like engine that drives the vehicle. A modern vehicle is also typically provisioned with an electrical system including: (i) a battery which provides a source of electric power for starting the vehicle's engine; and, (ii) one or more electric circuits or loads (e.g., headlights, clocks, electrically powered adjustable components such as seats, mirrors or steering columns, interior cabin lights, electric heaters for seats, mirrors, windows or the like, radios and/or other entertainment systems, electronic memories for recording radio station presets and/or user preferred seat and/or mirror positions, electronic navigation systems, etc.) that may also be selectively powered by the vehicle's battery. The trend of providing more electronic features and/or devices in a vehicle typically results in additional burden on the vehicle's battery and thus it becomes even more prudent to pay meaningful consideration to maintaining the health of the battery.
Typically, the vehicle's electrical system also includes an electric generator or other like device that is driven by the engine to produce electric power when the engine is running. For example, such a device is an alternating current generator (ACG), also commonly referred to as an alternator. Generally, the generator or ACG is arranged to selectively provide electric power to the aforementioned loads and/or to charge the battery.
A conventional generator or ACG of the type typically employed in an automotive vehicle is usually free to selectively operate in and/or cycle between one of two voltage output modes, e.g., depending on the operative state of the loads and/or demand for electric power from the generator or ACG. For example, in a first or HI output voltage mode, the output voltage of the generator or ACG is typically about 14.5 volts (V), and in a second or LO output voltage mode, the output voltage of the generator or ACG is typically about 12.5 V. Accordingly, when the electric power demand is relatively high or heavy, the generator or ACG normally operates in the HI output voltage mode, and when the electric power demand is relatively low or light, the generator or ACG normally operates in the LO output voltage mode. In customary automotive applications, the generator or ACG is generally free to selectively cycle between the two modes as the electric power demanded from the generator or ACG varies, e.g., due to changes in the operative states of the various loads.
In any event, while generally acceptable, the foregoing conventional operation of the ACG or generator may still not provide for suitable maintenance of the battery at a desired SOC in all circumstances. For example, continual operation of the ACG or generator in the HI voltage output mode, can result in overcharging of the battery and/or inefficient use of the vehicle's fuel—i.e., wasted fuel. Conversely, continual operation of the ACG or generator in a LO voltage output mode, can result in insufficient electrical power generation to effectively maintain the battery's SOC at or above a desired level.
Accordingly, a new and improved system and/or method is disclosed that overcomes the above-referenced problems and others by suitably controlling the output voltage of the ACG or generator.